1. Field of the Invention
The present invention pertains to fluid handling components and semiconductor fabrication equipment, and more particularly, pertains to a slow acting valve for use in the same.
2. Description of Prior Art
Various slow operating valves exist in other applications. Normally these components are used in very large volume systems and consequently are large, bulky and often inappropriate for use in "clean room" conditions in front end semiconductor fabrication equipment.
Prior art valves often had system shocks which occurred with the sudden actuation of a contact valve. The system shock would often cause debris and other particles lodged in the attached system to be dislodged only to pollute the entire system. These particles subsequently migrated to the process areas and onto the product substrate resulting in low die yields.
Other slow operating valves have used relatively large electric motors to activate screw drives or lever arms, which in turn actuate sliding ball valves or tapered shafts through relatively large longitudinal or rotational travel. These factors all contribute to higher cost, decreased reliability and significant particle generation.
The present invention provides a particle free valve for fluid or gas supply lines to minimize supply system shocks, which tend to dislodge particles previously captured in the supply system's filtration components or other dormant areas.